If it went in as a negligent driving offense instead of a dui then it's not an alcohol related offense. Remember the cops can arrest you for something, but getting a conviction on it is another matter. So the medical should not be a problem. As far as the airlines, I don't see any problems because he does not have a dui and his license did not even get suspended. He will just need to explain the driving offenses if they ask for them. If they hold it against you because they think it was dui then there is not much you can do. The important thing is that you avoided problems with the faa over the alcohol related issue.